1. Technical Field
The present invention relates to a disk drive.
2. Description of the Related Art
In addition to the traditional functions of reading and writing data, current disk drives available in the market provide an on-disk printing function (e.g. light-scribing), which is to record a photo, picture, or text, etc., desired by the user on the opposite side of the data-recording surface. In order to implement this on-disk printing function, it may be necessary to rotate a disk at a relatively low speed, unlike the typical modes for reading or recording data.
Whereas a disk drive in a desktop computer may generally rotate at about 10,500 rpm, and a disk drive in a laptop may rotate at about 5,400 rpm, a disk drive performing an on-disk printing function may rotate at a low speed of about 40 to 800 rpm. This may be due to technical limitations, as the on-disk printing technique, for burning the surface of a plastic disk using the laser diode of the optical pickup unit to print a desired photo, picture, or text, may not support high-speed rotations.
FIG. 1 is a cross sectional view of a disk drive according to the related art. As shown in FIG. 1, in order to operate the disk drive at a constant low speed, an encoder 140 for measuring the rotation speed of the spindle motor 100 may be mounted on a resin mold 130. However, in order for the encoder 140 to measure the rotation speed, a particular distance from the disk 10 may be required. Because of the various sizes in which the current disk drive 1000 is being produced, there may be difficulties in providing a particular distance between the encoder 140 and the disk 10.